CNC Programming Skills: Live Tool Drilling Cycles on a Fanuc Lathe

by S.K. Sinha

This is the third eBook in the series, “CNC Programming Skills.”This book is a part of the recently-published book, "Computer-Aided CNC Lathe, Probing & FMS," by the same author. Therefore, if one already has the CAM (Computer-Aided Manufacturing) book, this book need not be purchased. The CAM book is in form of a handbook for CNC lathe, covering almost everything related to programming (G-code programming as well as macro programming), tooling and operation.A good number of jobs require machining by both lathe and milling machines. A flange with bolt holes is one example. While turning and facing are done on a lathe, the holes need to be drilled on a milling machine (or a drilling machine). Involvement of two different machines with independent setup requirement increases the cycle time as well as production cost, despite the fact that the operation on the milling machine is very simple. To address this issue, these days higher-end lathes come equipped with live-tooling arrangement, allowing certain milling-like operations such as drilling, boring and tapping anywhere on the face of the workpiece, as well as in the radial direction at any angular position.The live tools can also be used for operations like polygon turning, and polar and cylindrical interpolations. In this book. we will restrict our discussion to drilling/boring/tapping operations only. To facilitate these operations, a number of built-in canned cycles are available. We would be explaining these with suitable examples in quite detail so as to cover nearly everything a programmer needs to know about them. Refer to the CAM book for other applications,The following excerpts from the book would give some idea of the style of presentation in the Front/Side Drilling Cycles (G83/G87):On a milling machine, two separate G codes are available for full-retraction peck drilling (suitable for holes with large length to diameter ratio) and high-speed (partial retraction) peck drilling applications (G83 and G73, respectively). On a lathe, however, there is only one G code available for both types. The selection between the two types is done through a parameter. When parameter 5101#2 is set to 0, G83/G87 become high-speed peck drilling cycles. On the other hand, when this parameter is set to 1, these become full-retraction peck drilling cycles. These cycles are explained in Figs. 2 and 3, which correspond to 5101#2 set to 0 and 1, respectively. Selection of retraction-type through this parameter is valid when parameter 5161#0 is set to 0 (the default value). When set to 1, G83.5/G87.5, and G83.6/G87.6 are used for partial and full retractions, respectively. While the full-retraction cycle draws the chips out of the hole after each peck (which makes it suitable for very deep holes), the high-speed cycle clears the chips in its final retraction only, though it does break the chips and allows the coolant to flood and cool the cutting zone as well as the tool..........G83 X(U)_ C(H)_ Z(W)_ R_ Q_ P_ F_ K_ M_ for front drillingG87 Z(W)_ C(H)_ X(U)_ R_ Q_ P_ F_ K_ M_ for side drillingwhereX(U)_ C(H)_ or Z(W)_ C(H)_: Hole position dataZ(W)_ or X(U): Position of the bottom of the holeR_: Position of R-pointQ_: Peck length in micron (one-tenth of thou in inch mode)P_: Dwell in millisecond at the bottom of the holeF_: FeedrateK_: Repeat count (non-modal data), if neededM_: M code for C-axis clamp, if needed.........

46 pages, Kindle Edition

Published February 10, 2015

Reviews

[Colin Dionne · Rating 5 out of 5]

A good introduction.

This is a decent intro to lathe live tool drilling and tapping cycles if you have existing G-Code knowledge. It covers tapping, drilling, and boring both axially and radially. I would recommend it for a refresh or a simple introduction.